From Mark Pickin, Easingwold, North Yorkshire, UK
The repeated reference to returning samples to Earth for study in your article “How to spot an alien” gives me a great sense of foreboding. As a virologist, I don’t understand how any rational scientific mind could ever contemplate bringing material back to Earth if, never mind because, it shows some signature of alien life. Yes, we have secure labs, but even the most secure has its weakest link (27 December, p 32).
